This invention relates generally to cooling mechanisms for buildings and more particularly to evaporative cooling systems.
Man has been able to adapt to climates from extreme cold to extreme heat. To do so, dwellings have been constructed which are adapted for the environmental conditions found, then the interior of the dwelling is either heated or cooled to bring the internal temperature within a xe2x80x9ccomfort rangexe2x80x9d. For desert climes, this means cooling the air within the rooms within the dwelling.
For dry/desert environments, the traditional choices for cooling the air is either through mechanical air conditioning or evaporative cooling. Mechanical air conditioning requires a great deal of electrical energy; hence, if possible, evaporative cooling is the technique of choice.
A typical evaporative cooler uses: a large electric motor with a fan; a small electric motor to pump the water; and, evaporative pads. The pump soaks the evaporative pads with water and the fan pulls air through the pads. As the air passes through the wetted pads, the air is cooled through the evaporative process. The now cooled air is pushed into the dwelling by the fan. To maintain a flow of air into the dwelling, windows or vents must be opened to allow the xe2x80x9cproperxe2x80x9d amount of air to flow through the house.
This design requires that the fan-motor pull and force the cold air. This is a difficult task as the pads, often layers of aspen fibers, restrict the easy flow of the air. Every time the air flow is deflected from its path by an obstruction, the air flow looses a significant of its velocity and its volumetric rate of flow.
It is clear there is a need for an improved evaporative cooling system.
The invention creates an evaporative cooler in which a series of evaporative pads are positioned in a spaced apart relationship within a housing unit.
In the preferred embodiment, these evaporative pads are relatively non-absorbent and are substantially circular in shape. Further, in the preferred embodiment, the pads are positioned vertically within the housing to allow the air to easily flow vertically between the pads.
Water from a reservoir is deposited onto the pads to moisten them. Once the pads have a thin layer of water on them, this layer of water serves to break the natural surface tension of the droplets being deposited on the pads. The breaking of the surface tension permits the droplets to spread out and coat the entire surface of the pads.
As the water on the pads evaporates, the surrounding air is cooled; thereby becoming denser and settling through the outlet at the bottom of the housing and into the area to be cooled. Note, no fan is used in this context; rather, air flow is created by the denser nature of cooled air.
As the cooled air falls from the housing, warm air is drawn into the top of the housing; the warm air is cooled by the water on the pads; and the cycle continues.
In one embodiment of the invention, the circular pads are held by a central spindle which rotates the pads (either electrically driven or through a water-wheel type of arrangement).
In reference to the preferred embodiment, the invention is ideal for homes with hip roofs for the desert area. The natural evaporation of water allows the air to flow unrestricted between the dampened round thin flat disks. In this embodiment, the pads are approximately xc2xc of an inch apart and centered upon a spindle that runs through the center of the disks. The disks rotate on the spindle and are kept moistened by drops of water falling from the channeled water to the outer-most disks which are adapted to serve as water-wheels to drive the spindle.
To create rotation of the spindle in the preferred embodiment, the two disks on the outside of the row of disks are formed into two water wheels (i.e. having buckets) which catch the flowing water from the water pump and keep the spindle and the disks turning.
The surface tension of the water on the disks keep the disks wet; the evaporation of the water keeps the disks cools; air is allowed to flow freely through the narrow spaces between the disks. Once the disks have been wetted, a drop of water falling anywhere on the wetted disk is dispersed into the dampened portion of the disk since the drop""s surface tension is broken by the water layer on the disk.
The arrangement of the preferred embodiment allows two opposing forces to work together, thereby greatly increasing the power of both opposing forces. The hot air rises without interference from the cold air as it falls. While the ambient hot air is rising, the cool air is channeled by a duct into the area to be cooled. This keeps the cold air from mixing with the hot air.
In one embodiment of the invention, the evaporative cooling system is placed over the attic of a building to cool the attic area. The hot air rises to the peak of the roof For hot air to escape easily, it must be replaced with other air. Therefore the cold air from the cooler is being sucked down the duct; encouraged by the force of the hot air trying to escape. This action increases the speed of the natural flow of the heavy cool air to fall.
In a short time, a blanket of cool air covers and penetrates all of the lower spaces between the joist in the attic. The cool air flows out through any low opening it can find. An opening made through the ceiling allows the excess cool air to flow into the room below, thereby circulating the air at the same time.
Using a second opening in the ceiling of one of the rooms below, the falling cool air forces the hotter air through the second opening. Preferably, this second opening extends above the layer of cool air within the attic. This lets the warm exiting air to reach the attic without disturbing the blanket of cool air covering the upper ceiling.
In another embodiment, the disks described above are replaced with strips of composition or metal. These strips are shaped with small xe2x80x9cVxe2x80x9d cuts which serve as spacers to keep narrow openings between adjoining strips. These strips are rolled into the desired diameter to make the evaporator.
To use this embodiment, the coiled material is set on a slight angles to the water allowing efficient air and water flow through the coiled material. A water wheel fastened to the upper end rotates this wheel and water dropping on the upper end of the turning wheel keeps the coiled evaporator damp.
While the preferred embodiment uses one small motor serving as the pump, other embodiments of the invention provide for a second motor to rotate the pad/disks within the housing.
A deflector serves to keep water from xe2x80x9cdrippingxe2x80x9d into the exit duct. A space under the deflector allows air to flow unobstructed to an exit duct. This duct carries the cooled air into to the area of choice.
The invention, together with various embodiments thereof, will be more fully explained by the accompanying drawings and the following descriptions thereof.